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Why Professional 1-Bit Sigma-Delta Conversion is a Bad Idea

Single-stage, 1-bit sigma-delta converters are, in principle, imperfectible. The authors prove this fact. The reason, simply stated, is that when properly dithered they are in constant overload. The consequence is that distortion, limit cycles, instability, and noise modulation can never be totally avoided. Recording, editing or storage systems based upon single-stage, 1-bit sigma-delta conversion and, in particular, professional systems using this type of conversion are thus a bad idea. In contrast multibit sigma-delta converters, which output linear PCM code (here, multibit refers to five or so bits in the converter), are in principle infinitely perfectible. They can be properly dithered to guarantee the absence of all distortion, limit cycles, and noise modulation. The audio industry is making a tragic mistake if it adopts 1-bit sigma-delta conversion as an archival format to replace multibit, linear PCM.: